With the exception of Andrew Neil and also Justin Webb the Lib Dems have been given an easy ride in their opposition to an in/out referendum on the European Union. They have escaped awkward questioning on this incredible shift in their policy.

At the last General Election the Lib Dem candidates stood on a manifesto with the following commitment:

The European Union has evolved significantly since the last public vote on membership over thirty years ago. Liberal Democrats therefore remain committed to an in/out referendum the next time a British government signs up for fundamental change in the relationship between the UK and the EU.

We believe that it is in Britain’s long-term interest to be part of the euro. But Britain should only join when the economic conditions are right, and in the present economic situation, they are not. Britain should join the euro only if that decision were supported by the people of Britain in a referendum.

Sure, the Lib Dems can point to the proviso about "next time" there is a proposal for "fundamental change." But are they saying they don't believe such a change is necessary? Are they saying that if the other EU countries wish such a change, the UK should block it?

The wording of the manifesto was not the only comment made by the Lib Dems on the matter. It should be seen in context.

For instance, there was this article in The Guardian by Nick Clegg in 2008, which declared:

"It's time we pulled out the thorn and healed the wound, time for a debate politicians have been too cowardly to hold for 30 years – time for a referendum on the big question. Do we want to be in or out? Nobody in Britain under the age of 51 has ever been asked that simple question. None of them were eligible to vote in that 1975 referendum. That includes half of all MPs. Two generations have never had their say."

Ed Davey, now a cabinet minister, also used to feel rather strongly in favour of an in/out referendum.

"This European Union that now exists is a far cry from the European Community that the British people voted to join in 1975. That is why I think we should have a referendum in Britain on the EU – and we should ask the people of Britain the big, crucial question that really matters – should we stay in the EU or withdraw."

Over thirty five years as a member state, we have seen the EU widen both its membership and share sovereignty from Mrs Thatcher’s Single European Act through to a succession of treaties agreed by both Conservative and Labour governments. In truth, the EU has changed beyond recognition from the EEC that Britain originally joined in 1973.

No-one under the age of fifty – including the current Foreign Secretary – has had a say on Britain’s membership of the EU. An in-out referendum would give people a vote on the broad issue rather than a narrower referendum on the Reform Treaty and allow us to promote the positive benefits of membership.

By doing so, we can also draw the poison from the debate about Europe’s future.

There was also the same message from Danny Alexander. In an article for the Inverness Courier, Mr Alexander said:

An in/out referendum would at least allow people to debate the fundamental issues that cause real concern to some. It would be a chance to lance the boil of euro-scepticism that has held Britain back in Europe for so long. That's why I voted last week for parliament to be allowed to debate the in/out option, and why I abstained on the much narrower idea of holding a vote on the specific details of this Treaty. Despite polls showing that by two to one people would prefer the broader debate that Liberal Democrats want, Conservative and Labour MPs voted to prevent Parliament even debating it.

If and when we get it, I look forward to campaigning for Britain to be at the heart of Europe. A real referendum would allow us to air all the facts, and decide whether European co-operation has — as I would argue — added to our ability to tackle vital international issues.

This policy originally came about when Sir Menzies Campbell was Lib Dem leader and announced:

"Let’s have an honest debate on the European Union followed by a real choice for the British people. That means a referendum on Britain’s membership of the EU. We would ask the British people the big question – whether to remain in the European Union or not.

“I will lead the Liberal Democrats at the forefront of that debate."

The Lib Dems have apologised for changing their policy on tuition fees. But they have yet to do so over their EU referendum u-turn. Yet they have less excuse for the latter than the former.

On increasing tuition fees they could argue that compromises were necessary due to being in a coalition. But on the in/out referendum the Lib Dems are in a perverse position. They are opposing their own policy – despite the Conservatives now embracing it.

The Lib Dems could also argue they had not realised their tuition fee policy was unaffordable. Again that alibi does not apply to the in/out referendum.

The Conservatives should be clear and proud about offering the people of this country a choice on EU membership. It is the right thing to do. It is also very popular – not only among those currently supporting UKIP but also among supporters or other parties.

Yesterday's YouGov poll showed this includes current Lib Dem supporters. Among that niche of the electorate there were 48% who favoured David Cameron's policy of renegotiation and then holding an in/out referendum. Another 17% of Lib Dems wanted an in/out referendum straight away. Only 30% of Lib Dems opposed having an in/out referendum at all.

So why have the Lib Dem politicians changed their minds? In 2007 they thought that a referendum result would favour continued EU membership. Now they aren't so sure – the opinion polling shows a big majority for withdrawal.

The Liberal Democrats don't trust the people. That is the honest reason for their u-turn. But it is not an explanation we are likely to hear from them.